Identify operation on webmap via REST

Is it possible to perform an Identify operation on an ArcGIS Online webmap via the REST API (not via the javascipt api), equivalent to identifying on an ArcGIS Server map service?

Big picture: We have quite a bit of code set up to access street centerline data from the identify operation on an ArcGIS Server map service. We're now finding clients who have their data on ArcGIS Online, and are trying to figure out a way to use our current code to access the data.

If it's not possible to identify on a web map, what options are available to access the ArcGIS Online data via a REST API?

On a side note, does ArcGIS Online offer publicly available street centerline data, and if so, how is it accessed?